The author provides information concerning newly farmed lands in the United States in paragraph 1 to support

A. a proposal by Frederick J. Turner that was later disputed by John D. Hicks.
B. an elaboration by John D. Hicks of thesis that formerly had been questioned by Turner.
C. the thesis that important changes occurred in the nature of international trade during the second half of the 19th century.
D. the view that the American frontier did not become closed during the 19th century or soon thereafter.